"During the first fifteen months of the LINZESS launch, we have
established a strong foundation of physician experience and payer
coverage for LINZESS. Now, while we continue advancing with prescribers
and payers, we are intensifying our efforts to educate appropriate
patients about LINZESS through a multi-channel, direct-to-consumer
patient awareness campaign," said Peter Hecht, chief executive officer
of Ironwood. "With commercial momentum, significant progress in our R&D
pipeline and the close of a $190 million equity offering, Ironwood
continues to grow into a leader in gastrointestinal therapeutics as we
work to maximize value for patients, health care providers and our
fellow shareholders."

First Quarter 2014 and Recent Highlights

LINZESS® (linaclotide)

LINZESS net product sales, as reported by Forest Laboratories, Inc.,
were $60.8 million in the first quarter of 2014, an increase of
approximately 19% quarter over quarter.

Nearly 240,000 LINZESS prescriptions were filled in the first quarter
of 2014, according to IMS Health, resulting in approximately 11%
growth in total prescriptions quarter over quarter. More than 800,000
LINZESS prescriptions have been filled by more than 260,000 unique
adult patients since the product's launch in December 2012, according
to IMS Health.

The total number of unique healthcare practitioners prescribing
LINZESS since launch reached more than 63,000 in the first quarter of
2014, according to IMS Health. This includes approximately 92% of high
prescribing gastroenterologists and approximately 76% of other high
prescribing healthcare practitioners, mostly primary care physicians.

More than 70% of people with commercial insurance and Medicare Part D
plans had unrestricted access to LINZESS as of March 2014.
Additionally, in March 2014, more than 70% of people with commercial
insurance had a copay of $30 or less, through formulary coverage or
the LINZESS Instant Savings Program.

Ironwood and Forest launched a DTC patient awareness campaign for
LINZESS designed to help adults suffering from IBS-C or CIC recognize
the symptoms of these disorders, describe their symptoms to their
doctor, and ask their doctor about LINZESS to help proactively manage
their disease. The extensive multi-channel campaign includes
television, print and online advertising; social media elements; an
updated brand website (www.linzess.com);
brochures in doctors' offices and pharmacies; and a waiting room TV
program.

Ironwood and Forest received Notices of Allowance from the United
States Patent and Trademark Office (USPTO) for two separate patent
applications covering the commercial formulation of LINZESS and
methods of using the product to treat patients with IBS-C or CIC. Both
of these patent applications are expected to issue in mid-2014 and
extend LINZESS patent protection by an additional five years into
2031. In addition, Ironwood was successful in defending a separate
linaclotide patent that was subject to an inter partes reexamination.
The USPTO confirmed that all claims in the patent are patentable,
concluding the review in Ironwood's favor and affirming the strength
of Ironwood's intellectual property around LINZESS.

Linaclotide (Rest of World)

Almirall, S.A., Ironwood's European partner, continues to
commercialize CONSTELLA® (linaclotide) in Europe, where it is the
first and only prescription product approved by the European Medicines
Agency for the symptomatic treatment of moderate to severe IBS-C in
adult patients. CONSTELLA has been approved for adult patients with
moderate to severe IBS-C and has been launched in 10 countries in
Europe, including the United Kingdom, Germany and most recently Italy,
with additional country launches expected in 2014. Almirall recently
announced that it intends to suspend commercialization of CONSTELLA in
Germany in May 2014, following an inability to reach agreement with
the German National Association of Statutory Health Insurance Funds on
a reimbursement price that reflects the innovation and value of
CONSTELLA. Almirall is assessing all possibilities to facilitate
continued access to CONSTELLA for appropriate patients in Germany.

Forest received marketing approval for linaclotide in Canada and
Mexico; launches in both countries are expected in mid-2014. Forest
has the rights to commercialize CONSTELLA in Canada and, through a
sublicense from Forest, Almirall has the rights to commercialize
LINZESS in Mexico.

Ironwood and AstraZeneca AB continue to enroll patients in a Phase III
clinical trial of linaclotide in adult patients with IBS-C in China.
The trial is expected to be completed in the first half of 2015.

Astellas Pharma Inc. completed a Phase II double-blind,
placebo-controlled, dose-ranging clinical trial of linaclotide in
adult patients with IBS-C in Japan. Preliminary top level data from
Astellas indicate higher responder rates for all linaclotide dose
groups versus placebo in the primary endpoint, although the difference
was not statistically significant. Linaclotide was well tolerated in
all dose groups within this study.

Research & Development

Ironwood continues to explore opportunities to evaluate linaclotide in
additional indications such as opioid-induced constipation, colorectal
cancer prevention, and pediatrics, as well as in combination with a
proton pump inhibitor and in a colonic delivery formulation. Ironwood
also is leveraging its gastrointestinal and guanylate cyclase
expertise to advance a robust pipeline of additional potential product
candidates, including IW‐3718 which is being studied for refractory
GERD, IW-9179 which is being studied for functional dyspepsia (FD) and
gastroparesis, and a soluble guanylate cyclase (sGC) program. Research
and development highlights for the quarter include:

Ironwood initiated dosing of its investigational bile acid
sequestrant, IW‐3718, in a Phase IIa clinical study for patients
with GERD symptoms who have not responded adequately to treatment
with a proton pump inhibitor. Data from this trial are expected in
the first half of 2015.

Ironwood ended its exploratory Phase IIa study of IW-9179 in FD
prior to completing enrollment, due to challenges with the
rigorous enrollment exclusion criteria in the trial. Data analysis
is ongoing but preliminary data support continued development.
Ironwood continues to define a path forward for IW-9179 in FD. In
parallel, Ironwood plans to initiate a Phase IIa clinical trial of
IW-9179 in patients with gastroparesis in the first half of 2015.

Ironwood identified a development candidate in its sGC program,
which targets a proven mechanism for treating pulmonary arterial
hypertension (PAH) and other cardiovascular diseases with the
potential for broad therapeutic utility both inside and outside of
the CV therapeutic category. Preclinical development is ongoing.

Corporate and Financials

Collaborative Arrangements Revenue. Collaborative arrangements
revenue was approximately $14.6 million in the first quarter of 2014
compared with approximately $5.0 million in the fourth quarter of
2013. The collaborative arrangements revenue consisted of $8.4 million
in revenue associated with Ironwood's share of the net profits and
losses from the sales of LINZESS in the U.S., as well as $6.2 million
in sales of linaclotide active pharmaceutical ingredient (API),
amortization of deferred revenue associated with consideration
received from Ironwood's collaboration with Astellas, revenue
recognized under the collaboration with AstraZeneca, and milestone and
royalty payments based on sales of CONSTELLA in Europe from Almirall.

Operating Expenses. Operating expenses were approximately $57.1
million in the first quarter of 2014, including non-reoccurring
charges totaling $4.3 million associated with Ironwood's headcount
reduction in January 2014, as compared to approximately $51.2 million
in the fourth quarter of 2013. Operating expenses consisted of
approximately $27.1 million in research and development (R&D)
expenses, which included $2.7 million in non-cash share-based
compensation expense, and approximately $30.0 million in selling,
general and administrative (SG&A) expenses, which included $3.4
million in non-cash share-based compensation expense.

Collaboration Expense. Ironwood records its share of the net
profits and losses from the sales of LINZESS in the U.S. on a net
basis and presents the settlement payments from and to Forest as
collaborative arrangements revenue or collaboration expense,
respectively. In the first quarter of 2014 and the fourth quarter of
2013, Ironwood recorded the settlement payments from Forest of
approximately $8.4 million and $2.9 million, respectively, as
collaborative arrangements revenue, and no collaboration expense was
recorded.

Interest Expense. Interest expense was approximately $5.3
million in the first quarter of 2014 in connection with the $175
million debt financing executed in January 2013.

Net Loss. Net loss was approximately $49.6 million, or $0.38
per share, in the first quarter of 2014, as compared to approximately
$52.0 million, or $0.43 per share, in the fourth quarter of 2013.

Cash Position. Ironwood ended the first quarter of 2014 with
approximately $332 million of cash, cash equivalents and
available-for-sale securities, up from approximately $198 million as
of the end of 2013. Ironwood used approximately $58 million of cash
for operations during the first quarter of 2014.

Public Equity Offering. In the first quarter of 2014, Ironwood
sold 15,784,325 shares of its Class A common stock through a firm
commitment, underwritten public offering at a price to the public of
$12.75 per share. As a result of the offering, Ironwood received
aggregate net proceeds, after underwriting discounts and commissions
and other offering expenses, of approximately $190.4 million.

2014 Financial Guidance. Ironwood today reiterated its
financial guidance for 2014. Total operating expenses are expected to
be in the range of $215 to $245 million, consisting of $105 to $120
million in R&D expenses and $110 to $125 million in SG&A expenses.
Non-linaclotide R&D expenses are expected to be approximately 45% of
total R&D expenses. In addition, Ironwood today reiterated its
financial guidance for the Forest and Ironwood total 2014 marketing
and sales expenses for LINZESS, which it continues to expect to be in
the range of $240 to $270 million.

Conference Call Information

Ironwood will host a conference call and webcast at 8:30 a.m. Eastern
Time, on Tuesday, April 29, to discuss its first quarter 2014 and recent
business activities. Individuals interested in participating in the call
should dial (877) 643-7155(U.S. and Canada) or (914) 495-8552
(international) using conference ID number 3733415. To access the
webcast, please visit the Investors section of Ironwood's website at www.ironwoodpharma.com
at least 15 minutes prior to the start of the call to ensure adequate
time for any software downloads that may be required. The call will be
available for replay via telephone starting today at approximately 11:30
a.m. Eastern Time, on April 29, running through 11:59 p.m. Eastern Time
on May 6, 2014. To listen to the replay, dial (855) 859-2056 (U.S. and
Canada) or (404) 537-3406 (international) using conference ID number
3733415. The archived webcast will be available on Ironwood's website
for 14 days beginning approximately one hour after the call has
completed.

About LINZESS (linaclotide)

LINZESS is the first and only guanylate cyclase-C (GC-C) agonist
approved by the FDA and is indicated for the treatment of both irritable
bowel syndrome with constipation (IBS-C) and chronic idiopathic
constipation (CIC) in adults. LINZESS is a once-daily capsule that helps
relieve the abdominal pain and constipation associated with IBS-C, as
well as the constipation, infrequent stools, hard stools and incomplete
evacuation associated with CIC. The recommended dose is 290 mcg for
IBS-C patients and 145 mcg for CIC patients. LINZESS should be taken at
least 30 minutes before the first meal of the day.

LINZESS is thought to work in two ways based on nonclinical studies.
LINZESS binds to the GC-C receptor locally, within the intestinal
epithelium. Activation of GC-C results in increased intestinal fluid
secretion and accelerated transit and a decrease in the activity of
pain-sensing nerves in the intestine. The clinical relevance of the
effect on pain fibers, which is based on nonclinical studies, has not
been established.

In placebo-controlled Phase III clinical trials of more than 2,800
adults, LINZESS was shown to reduce abdominal pain in IBS-C patients and
increase bowel movement frequency in both IBS-C patients and CIC
patients. Improvement in abdominal pain and constipation occurred in the
first week of treatment and was maintained throughout the 12-week
treatment period. Maximum effect on abdominal pain was seen at weeks 6-9
and maximum effect on constipation occurred during the first week. When
a subset of LINZESS-treated patients in the trials were switched to
placebo, they reported their symptoms returned toward pretreatment
levels within one week, while placebo-treated patients switched to
LINZESS reported symptom improvements. LINZESS is contraindicated in
pediatric patients up to 6 years of age. The use of LINZESS in pediatric
patients 6 through 17 years of age should be avoided. In nonclinical
studies, administration of a single, clinically relevant adult oral dose
of linaclotide caused deaths in young juvenile mice. LINZESS has not
been studied in pediatric patients. In adults with IBS-C or CIC treated
with LINZESS, the most commonly reported adverse event was diarrhea.

Ironwood and Forest Laboratories, Inc. are co-promoting LINZESS in the
United States. Linaclotide is marketed by Almirall, S.A. for the
treatment of adults with moderate to severe IBS-C in Europe under the
brand name CONSTELLA®. Ironwood also has partnered with Astellas Pharma
Inc. for development and commercialization of linaclotide in Japan and
with AstraZeneca for development and commercialization in China.

About CONSTELLA (linaclotide)

Linaclotide is a Guanylate Cyclase-C receptor agonist (GCCA) with
visceral analgesic and secretory activities. Linaclotide is a 14-amino
acid synthetic peptide structurally related to the endogenous guanylin
peptide family. Both linaclotide and its active metabolite bind to the
Guanylate Cyclase-C receptor, on the luminal surface of the intestinal
epithelium. Through its action at GC-C, linaclotide has been shown to
reduce visceral pain and increase GI transit in animal models and
increase colonic transit in humans. Activation of GC-C results in an
increase in concentrations of cyclic guanosine monophosphate (cGMP),
both extracellularly and intracellularly. Extracellular cGMP decreases
pain-fiber activity, resulting in reduced visceral pain in animal
models. Intracellular cGMP causes secretion of chloride and bicarbonate
into the intestinal lumen, through activation of the cystic fibrosis
transmembrane conductance regulator (CFTR), which results in increased
intestinal fluid and accelerated transit.

Linaclotide was discovered by scientists at Ironwood and is marketed by
Almirall, S.A. for the treatment of adults with moderate to severe IBS-C
in Europe under the brand name CONSTELLA, through a license agreement
between the two companies.

About Ironwood Pharmaceuticals

Ironwood Pharmaceuticals (NASDAQ: IRWD) is focused on creating medicines
that make a difference for patients, building value to earn the
continued support of our fellow shareholders, and empowering our team to
passionately pursue excellence. We discovered, developed and are
commercializing linaclotide, which is approved in the United States and
a number of other countries. Our pipeline priorities include exploring
further opportunities for linaclotide, as well as leveraging our
therapeutic expertise in gastrointestinal disorders and our
pharmacologic expertise in guanylate cyclases to address patient needs
across the upper and lower gastrointestinal tract. Ironwood was founded
in 1998 and is headquartered in Cambridge, Mass. Connect with us at www.ironwoodpharma.com
or on Twitter at www.twitter.com/ironwoodpharma;
information that may be important to investors will be routinely posted
in both these locations.

LINZESS® and CONSTELLA® are trademarks owned by Ironwood
Pharmaceuticals, Inc. Any other trademarks referred to in this press
release are the property of their respective owners. All rights reserved.

Important Safety Information

WARNING: PEDIATRIC RISK

LINZESS is contraindicated in pediatric patients up to 6 years
of age. Use should be avoided in pediatric patients 6 through 17
years of age. In nonclinical studies, administration of a single,
clinically relevant adult oral dose of linaclotide caused deaths
in young juvenile mice.

Contraindications

LINZESS is contraindicated in pediatric patients up to 6 years of age.

LINZESS is contraindicated in patients with known or suspected
mechanical gastrointestinal obstruction.

Warnings and Precautions

Pediatric Risk

LINZESS is contraindicated in pediatric patients up to 6 years of age.
In nonclinical studies, deaths occurred within 24 hours in young
juvenile mice (1 to 3 week-old mice; approximately equivalent to human
pediatric patients less than 2 years of age) following administration
of one or two daily oral doses of linaclotide.

Use of LINZESS should be avoided in pediatric patients 6 through 17
years of age. Linaclotide did not cause deaths in older juvenile mice
(approximately equivalent to humans age 12 to 17 years). Although
there were no deaths in older juvenile mice, given the deaths in young
juvenile mice and the lack of clinical safety and efficacy data in
pediatric patients, use of LINZESS should be avoided in pediatric
patients 6 through 17 years of age.

Diarrhea

Diarrhea was the most common adverse reaction of LINZESS-treated
patients in the pooled IBS-C and CIC double-blind placebo-controlled
trials. Severe diarrhea was reported in 2% of LINZESS-treated
patients. The incidence of diarrhea was similar in the IBS-C and CIC
populations.

Patients should be instructed to stop LINZESS if severe diarrhea
occurs and to contact their healthcare provider, who should consider
dose suspension.

This press release contains forward-looking statements. Investors are
cautioned not to place undue reliance on these forward-looking
statements, including, but not limited to, statements about our
development and commercialization plans for linaclotide, our product
candidates and the programs in our pipeline, including statements
regarding our LINZESS patient awareness campaign; the launch and
commercialization of linaclotide in additional countries and the timing
thereof, as well as expectations regarding the continued
commercialization of CONSTELLA in Germany; the anticipated timing of
pre-clinical and clinical developments; the timing and results of
clinical and pre-clinical trials; the expected issuance of patents and
the period of patent protection associated therewith, if issued; the
strength of the intellectual property protection for our product and
product candidates; and our company's financial performance and results
and guidance related thereto, including our projected 2014 operating
expenses (including certain research and development expenses and
selling, general and administrative expenses) and marketing and sales
expense for LINZESS. Each forward‐looking statement is subject to risks
and uncertainties that could cause actual results to differ materially
from those expressed or implied in such statement. Applicable risks and
uncertainties include, but are not limited to, those related to
pre-clinical and clinical development, manufacturing, and formulation
development; decisions made by regulatory authorities; decisions made by
the USPTO and its foreign counterparts; intellectual property rights of
competitors or potential competitors; efficacy, safety and tolerability;
competition in disease states; the commercial potential of LINZESS and
our product candidates; the risk that we may never get sufficient patent
protection for our product and product candidates; the risk that our
planned investments do not have the anticipated effect on LINZESS or our
company revenues; the risk that we are unable to manage our operating
expenses over the year due to foreseeable or unforeseeable events or
occurrences; and the risk that we and our partner, Forest Laboratories,
Inc., are unable to commercialize LINZESS within the guided range of
expenses. Applicable risks also include those that are listed under the
heading "Risk Factors" and elsewhere in Ironwood's Annual Report on Form
10‐K for the year ended December 31, 2013, in addition to the risk
factors that are listed from time to time in Ironwood's Annual Reports
on Form 10‐K, Quarterly Reports on Form 10‐Q and any other subsequent
SEC filings. Ironwood undertakes no obligation to update these
forward-looking statements to reflect events or circumstances occurring
after this press release. Except as otherwise noted, these
forward-looking statements speak only as of the date of this press
release. All forward‐looking statements are qualified in their entirety
by this cautionary statement.

Condensed Consolidated Balance Sheets

(In thousands)

(unaudited)

March 31,2014

December 31,2013

Assets

Cash, cash equivalents and available-for-sale securities

$

332,269

$

197,602

Accounts receivable, net

10,337

3,213

Inventory

23,413

22,145

Prepaid expenses and other current assets

5,286

6,168

Total current assets

371,305

229,128

Property and equipment, net

35,524

37,376

Other assets

12,042

12,458

Total assets

$

418,871

$

278,962

Liabilities and Stockholders' Equity

Accounts payable and accrued expenses

$

24,032

$

32,037

Current portion of capital lease obligations

1,156

1,139

Current portion of deferred rent

2,803

2,790

Current portion of deferred revenue

6,128

5,074

Current portion of notes payable

4,381

—

Total current liabilities

38,500

41,040

Capital lease obligations

2,842

3,134

Deferred rent

8,127

8,822

Deferred revenue

10,147

11,416

Notes payable

170,312

174,672

Other liabilities

—

1,653

Total stockholders' equity

188,943

38,225

Total liabilities and stockholders' equity

$

418,871

$

278,962

Condensed Consolidated Statements of Operations

(In thousands, except per share amounts)

(unaudited)

Three Months Ended

March 31,

2014

2013

Revenue

$

14,605

$

3,255

Cost and expenses:

Cost of revenue

1,924

1,231

Research and development (1)

27,144

32,753

Selling, general and administrative (1)

29,924

33,374

Collaboration expense

—

24,730

Total cost and expenses

58,992

92,088

Loss from operations

(44,387

)

(88,833

)

Other income (expense), net

(5,239

)

(5,069

)

Net loss

$

(49,626

)

$

(93,902

)

Net loss per share—basic and diluted

$

(0.38

)

$

(0.87

)

Weighted average number of common shares used in net loss per
share —basic and diluted

129,745

108,073

(1) Non-cash compensation expenses reflected in the condensedconsolidated
statements of operations are as follows:

Research and development

$

2,690

$

2,224

Selling, general and administrative

$

3,384

$

3,051

LINZESS U.S. Collaboration Revenue/Expense Calculation1

(in thousands)

(unaudited)

Three Months Ended

March 31,

2014

2013

LINZESS net sales

$

60,812

$

4,502

Commercial costs and expenses2

59,916

71,040

Net profit (loss) on sales of LINZESS

$

896

$

(66,538

)

Ironwood's share of net profit (loss)

$

448

$

(33,269

)

Ironwood's selling, general and administrative expenses3

$

7,999

$

8,539

Ironwood's collaboration expense

$

—

$

(24,730

)

Ironwood's collaborative arrangement revenue

$

8,447

$

—

1 Ironwood collaborates with Forest on the development and
commercialization of linaclotide in North America. Under the terms of
the collaboration agreement, Ironwood receives 50% of the net profits
and bears 50% of the net losses from the commercial sale of LINZESS in
the U.S. The purpose of this table is to present calculations of
Ironwood's share of net profit (loss) generated from the sales of
LINZESS in the U.S. and Ironwood's collaboration revenue/expense;
however, the table does not present the research and development
expenses related to LINZESS in the U.S. that are shared equally between
the parties under the collaboration agreement.

2 Includes cost of goods sold incurred by Forest as well as
selling, general and administrative expenses incurred by Forest and
Ironwood that are attributable to the cost-sharing arrangement between
the parties.

3 Includes Ironwood's selling, general and administrative
expenses attributable to the cost-sharing arrangement with Forest.